Silicon Origin:widely distributed in dusts,sands,clay in the forms of silicon dioxide(silica)or silicates Characteristics:1.amorphous and crystalline silicon,2.diamond cubic crystal structure,3semiconductor (E=1.12 eV) Preparation:conversion of silica(SiO2) >Carbothermal reduction→SiO,+2C→Si+2CO2 SiC+SiO2→3Si+2C0 >Aluminothermal reduction-3 SiO,+4 Al->3 Si+2 Al2O3 quartz,agate,agate.4 Silicon • Origin：widely distributed in dusts, sands, clay in the forms of silicon dioxide (silica) or silicates • Characteristics: 1. amorphous and crystalline silicon， 2. diamond cubic crystal structure， 3.semiconductor (Eg=1.12 eV) • Preparation：conversion of silica (SiO2 )  Carbothermal reduction → SiO2 + 2 C → Si + 2 CO2 SiC + SiO2 → 3 Si + 2 CO  Aluminothermal reduction → 3 SiO2 + 4 Al → 3 Si + 2 Al2O3 quartz, agate, agate